Genetic polymorphism of the human apolipoproteins A and E

Abstract

The technique of horizontal, thin layer isoelectric focusing was used to demonstrate the polymorphism of the apolipoproteins E, A-I, A-II and A-IV.

Polymorphic forms of apo E were detected after ultracentrifugation of plasma, delipidation of VLDL and isoelectric focusing of the remaining protein. The six common phenotypes, homozygotes E 2/2, E 3/3, E 4/4 and the heterozygotes E 2/3, E 2/4, E 3/4, of apo E were demonstrated.

A simplified one step screening method, not requiring ultracentrifugation techniques, was used to demonstrate the A apolipoproteins. As the method uses native serum, epo A-IV was detected as well as apo A-I and apo A-II.

The one step screening technique demonstrated reduced levels of apo A-I and A-II in a patient homozygous for Tangier disease. It was also utilised to screen patients undergoing cardiac catheterisation, no variants of apo A-I and A-II were detected in this patient population. The presence of a minor apo A-IV variant in these patients requires confirmation by other techniques.